The geomorphological analysis as a basis for the study of native vegetation. Sierra Chica de Zonda, eastern Precordillera of Argentina

The characteristics of native vegetation and the geomorphological properties of a region are interrelated, so that any change in one of them affects the other. The aim of this study was to identify the geomorphic units and to record information (species, coverage) of the native vegetation of the Sierra Chica de Zonda in order to investigate the relationships between vegetation distribution and geomorphic environments. Sierra Chica de Zonda is located in the Monte Phytogeographic Province of Argentina. Morphogenetic and morphodynamic criteria were used for the geomorphological analysis. For the vegetation analysis, sampling transects of 50 m long were traced, and presence, coverage, diversity and species richness were evaluated every 0.5 m using the Point Quadrat modified method. The Shannon-Wiener's biodiversity index and species richness were calculated. The data were analyzed using the Shapiro Wilk's test and Kruskal Wallis's non-parametric test. The relief was classified in two groups: mountainous and piedmonts reliefs; the latter was divided into colluvial and alluvial fans. The morphodynamic analysis indicated that alluvial fans could be subdivided into i) current dynamic and functional units, and ii) stable oldest nonfunctional units. Over the geomorphological units, 37 native plant species were identified, distributed in 17 families, with significant differences in coverage (Kruskal Wallis p=0.001). The morphodynamics of the region, characterized by the type and intensity of the processes, was different in each geomorphological unit. These processes play an important role on the distribution, diversity and vegetation cover by creating (or not) favorable conditions for the development of native plant species. The geomorphological information and the coverage and distribution of native vegetation was integrated in a final digital map.